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commandlinefu.com is the place to record those command-line gems that you return to again and again.

Delete that bloated snippets file you've been using and share your personal repository with the world.
That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and
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Psst. Open beta.

Wow, didn't really expect you to read this far down. The latest iteration of the site is in open beta. It's a gentle open beta-- not in prime-time just yet. It's being hosted over at UpGuard (link) and you are more than welcome to give it a shot. Couple things:

» The open beta is running a copy of the database that will not carry over to the final version. Don't post anything you don't mind losing.

» If you wish to use your user account, you will probably need to reset your password.

Your feedback is appreciated via the form on the beta page. Thanks! -Jon & CLFU Team

This command takes advantage of the ext4 filesystem's resistance to fragmentation.

By using this command, files that were previously fragmented will be copied / deleted / pasted essentially giving the filesystem another chance at saving the file contiguously. ( unlike FAT / NTFS, the *nix filesystem always try to save a file without fragmenting it )

My command only effects the home directory and only those files with your R/W (read / write ) permissions.

There are two issues with this command:

1. it really won't help, it works, but linux doesn't suffer much (if any ) fragmentation and even fragmented files have fast I/O

2. it doesn't discriminate between fragmented and non-fragmented files, so a large ~/ directory with no fragments will take almost as long as an equally sized fragmented ~/ directory

The benefits i managed to work into the command:

1. it only defragments files under 16mb, because a large file with fragments isn't as noticeable as a small file that's fragmented, and copy/ delete/ paste of large files would take too long

2. it gives a nice countdown in the terminal so you know how far how much progress is being made and just like other defragmenters you can stop at any time ( use ctrl+c )

3. fast! i can defrag my ~/ directory in 11 seconds thanks to the ramdrive powering the command's temporary storage

bottom line:

1. its only an experiment, safe ( i've used it several times for testing ), but probably not very effective ( unless you somehow have a fragmentation problem on linux ). might be a placebo for recent windows converts looking for a defrag utility on linux and won't accept no for an answer

Just a quick hack to give reasonable filenames to TrueType and OpenType fonts.

I'd accumulated a big bunch of bizarrely and inconsistently named font files in my ~/.fonts directory. I wanted to copy some, but not all, of them over to my new machine, but I had no idea what many of them were. This script renames .ttf files based on the name embedded inside the font. It will also work for .otf files, but make sure you change the mv part so it gives them the proper extension.

BUGS: Well, like I said, this is a quick hack. It grew piece by piece on the command line. I only needed to do this once and spent hardly any time on it, so it's a bit goofy. For example, I find 'rev | cut -f1 | rev' pleasantly amusing --- it seems so clearly wrong, and yet it works to print the last argument. I think flexibility in expressiveness like this is part of the beauty of Unix shell scripting. One-off tasks can be be written quickly, built-up as a person is "thinking aloud" at the command line. That's why Unix is such a huge boost to productivity: it allows each person to think their own way instead of enforcing some "right way".

On a tangent: One of the things I wish commandlinefu would show is the command line HISTORY of the person as they developed the script. I think it's that conversation between programmer and computer, as the pipeline is built piece-by-piece, that is the more valuable lesson than any canned script.

Some commands (such as sed and perl) have options to support in-place editing of files, but many commands do not. This shell function enables any command to change files in place. See the sample output for many examples.

The function uses plain sh syntax and works with any POSIX shell or derivative, including zsh and bash.

Change run control links from start "S" to stop "K" (kill) for whatever run levels in curly braces for a service called "myservice". NEWFN variable is for the new filename stored in the in-line shell. Use different list of run levels (rc*.d, rc{1,3,5}.d, etc.) and/or swap S with K in the command to change function of run control links.